First, don’t tell me that the answer is just to “not bottle things up”, because that’s objectively incorrect too. Society doesn’t want you to have any negative emotions. I need to know how to not express negative emotions at all whatsoever unless I’m alone. I know it can be done because it is done in many other people on the planet.
Edit: Ok so I think one of the things I want to try doing next is ask for a med change from my psych provider.
You are not your thoughts, nor are you your emotions. You are the observer of those things. Somebody presses your buttons, but it is your choice whether or not those buttons fire. For example if a child said some hurtful things to you, would it have the same impact as an adult? I should hope not. What is stopping you from viewing somebody as a child, especially if they are acting like one?
In addition to cardio, try breathing and cold water. Always breathe through your nose, even when running. Try to breathe through your nose as a cold shower takes your breath away. Or go for the full ice bath. An ice bath tells your body (the producer of anger emotions and chemicals), “hey, I’m in control here, you are not good at assessing threats”. The mind follows the breath, or the breath follows the mind.
But if I’m being honest I’ve always had a hot temper, and what is really helping me is Lithium. It allows me to observe anger without being overwhelmed by it.